1. Field of Invention
The present invention relates to a method for forming a metal wire of a semiconductor device, and in particular, to a method for alternately forming a plurality of metal wires between insulation films, to prevent electrical short between adjacent metal wires and to improve process margin in a lithography process and an etching process.
2. Information Disclosure Statement
In general, the metal wire has a role of electrically connecting a cell and a peripheral circuit in all semiconductor devices, however, it is difficult to form a metal wire of a preferable profile due to difference in topology between the cell and the peripheral circuit. In particular, as the semiconductor is more densely integrated, it is more difficult to form the metal wire of the preferable profile.
FIG. 1 is a plane view of a conventional photomask used for forming dense metal wires.
The photomask A is manufactured by forming a first, second, third and fourth Chrome pattern P1, P2, P3 and P4 on a quartz substrate B. To form the metal wire to a maximum degree of density, it is preferable to form the width of each pattern of the first, second, third and fourth Chrome patterns P1, P2, P3 and P4 and the width of space between the patterns to be the same.
In case where the photomask A having the above described construction is manufactured to correspond to a stepper (not shown) which can form a minimum pattern width of 0.35 .mu.m, it is possible to form metal wires of preferable profile having the width of 0.35 .mu.m in a flat plate having no difference in the topology, however, a problem occurs with plates having difference in the topology in that the electrical short occurs between the adjacent metal wires because the profile of the metal wires become aggravated.
Therefore, an object of the present invention is to provide the method for forming a metal wires of a semiconductor device which can prevent the electrical short between the adjacent metal wires by alternately forming metal wires between insulation films.
Other object of the present invention is to improve the process margin in the lithography process and the etching process by utilizing two photomasks which correspond to a conventional photomask for metal wire.